Travel velocity detecting apparatus in mobile communication system

ABSTRACT

A travel velocity detector is installed in a mobile telephone station such as a portable telephone or a car telephone. The travel velocity detector adapts a received power level to a travel velocity of the mobile station. Two receiving circuits receive communication waves via respective antennas and output respective power levels E1 and E2 therefrom. The detected powers E1 and E2 are compared with each other to determine which of the powers is greater. A variation of the comparison result is then detected. The number of detected variations, corresponding to a switching frequency, is then counted during a preset time period. A relative travel velocity between the mobile station and an opposite transmitting station is estimated on the basis of the number of the counted variations.

TECHNICAL FIELD

The present invention generally relates to an apparatus installed in amobile station, such as a portable telephone, or a car telephone andserving to detect a travel velocity of such a mobile station from radiocommunication waves. More particularly, the present invention relates toa travel velocity detecting apparatus which is employed in a mobilecommunication system to adapt a received power level to the travelvelocity of the mobile station while further detecting the accelerationand travel distance of the mobile station.

BACKGROUND ART

It is observed of late that the demand for the above-described mobilestation is on a remarkable upward trend, and therefore other apparatusand devices ancillary to the mobile communication system are alsoextended in compliance with such increasing requirements. Under thecurrent circumstances where the whole mobile communication system is inan enhanced state of progress, it becomes necessary to use many radiofrequencies for communication.

However, there exist limits in the usable radio frequencies. For thepurpose of achieving effective utilization of radio frequencies,introduction of some novel techniques is now being studied, includingdynamic channel allocation control and so forth. In such dynamic channelallocation control, it is pointed out that data relative to the travelvelocity of a caller is rendered important. Consequently the travelvelocity of a caller, i.e., the velocity of a mobile station, needs tobe detected.

Although detection of the travel velocity of a mobile station isimportant, as in this example, an adequate apparatus designed fordetecting the travel velocity of a mobile station from radiocommunication waves, as mentioned above in the "Technical Field", hasnot been available in the prior art. The travel velocity of a mobilestation is usable also as an essential parameter in radio circuitcontrol such as "hand-off" control executed when a mobile station runsin a radio zone. In addition, it has recently become known that thetravel distance and the acceleration of a mobile station are alsoconsidered to be important parameters. However, a conventional apparatusis not available for acquiring the travel distance and the accelerationfrom radio communication waves.

By the way, there is observed in the field of mobile communication, aphenomenon termed "fading" wherein the received power level is sharplyvaried. Even under such circumstances, it is necessary to perform aprecise decision of the present radio zone and an accurate detection ofthe received power level which is required for controlling thetransmission power. The temporal variation pitch of the received powerlevel caused by such fading is proportional to the travel velocity ofthe mobile station.

In detecting the received power level, generally, a temporal averagingprocess is executed. Since averaging time is determined by the variationpitch, a short time is sufficient for rapid variations, but a longaveraging time is needed for slow and gentle variations. For example,the variation pitch is shortened in accordance with an increase of thevelocity of the mobile station, so that the number of variation samplesextracted per unit time for the averaging process is rendered greater.More specifically, in the case of rapid variations, the requiredaveraging time is short as mentioned.

Meanwhile if the velocity of the mobile station is lowered, thevariation pitch is rendered longer to consequently reduce the number ofsamples extracted per unit time for the averaging process. That is, inslow and gentle variations, the required averaging time is prolonged.For this reason, another problem has been existent in the prior artheretofore that, even when a short averaging time is sufficient toexecute the process, a long averaging time is required in conformitywith the case where the necessary averaging time is long.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a travelvelocity detecting apparatus which is employed in a mobile communicationsystem for solution of the above-described problems observed in theprior art and is capable of detecting the travel velocity, traveldistance and acceleration of a mobile station from radio communicationwaves without the necessity of referring to the velocity data of amobile body itself, such as a car.

Another object of the present invention resides in providing a travelvelocity detecting apparatus which is capable of adapting, in a mobilecommunication system, a received power level to the travel velocity of amobile station.

According to a first principle of the present invention, there isprovided a travel velocity detecting apparatus in a mobile communicationsystem, which comprises receiving means of two or more channels capableof receiving radio waves and detecting the powers thereof; comparatormeans connected operatively to the receiving means of two or morechannels for mutually comparing the powers detected by the receivingmeans of two or more channels so as to determine the greater power;variation detector means connected operatively to the comparator meansfor detecting the variations of the comparison result outputted from thecomparator means; counter means connected operatively to the variationdetector means for counting the number of the detected variations for apreset time; and converter means connected operatively to the countermeans for calculating the relative travel velocity between the relevantmobile station and the opposite station on the basis of the numericalvalue obtained by the counting operation.

According to a second principle of the present invention, there isprovided a travel velocity detector in a mobile communication system,which comprises level detector means for detecting the received powerlevel; sampling means connected operatively to the level detector meansfor sampling the received power level; memory means connectedoperatively to the sampling means for storing the sampled power levelstherein and then outputting the stored levels therefrom in the order ofthe storage; difference calculator means connected operatively to boththe memory means and the sampling means for calculating the differencebetween the power levels outputted from the sampling means and thememory means; comparator means connected operatively to the differencecalculator means for executing a comparison to decide whether thedifference obtained by the difference calculator means has exceeded apreset threshold value or not; counter means connected operatively tothe comparator means for counting the comparison results outputted fromthe comparator means for a predetermined time, thereby obtaining anumerical value which indicates the number of times that the differencehas exceeded the preset threshold value; and converter means connectedoperatively to the counter means for calculating the relative travelvelocity between the relevant mobile station and the opposite station onthe basis of the numerical value obtained by the counter means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram illustrating the relationship between abranch (receiving section) switching frequency and a Doppler frequencyin the first principle of the present invention;

FIG. 2 graphically shows theoretical values and experimental valuesrepresenting the relationship between the branch switching frequency andthe Doppler frequency in the first principle of the invention;

FIG. 3 shows a probability density distribution of temporal differentialcoefficients relative to the envelope of a received signal when theDoppler frequency f_(D) is high in the second principle of theinvention;

FIG. 4 shows a probability density distribution of temporal differentialcoefficients relative to the envelope of a received signal when theDoppler frequency f_(D) is low in the second principle of the invention;

FIG. 5 shows temporal differences of the envelope when the Dopplerfrequency f_(D) is high in the second principle of the invention:

FIG. 6 shows temporal differences of the envelope when the Dopplerfrequency f_(D) is low in the second principle of the invention;

FIG. 7 graphically shows the relationship between the number N_(3dB) oflevel variations (per second) and the Doppler frequency f_(D) in thesecond principle of the invention;

FIG. 8 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 1st embodiment of theinvention;

FIG. 9 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 2nd embodiment of theinvention;

FIG. 10 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 3rd embodiment of theinvention;

FIG. 11 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 4th embodiment of theinvention;

FIG. 12 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 5th embodiment of theinvention;

FIG. 13 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 6th embodiment of theinvention;

FIG. 14 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 7th embodiment of theinvention;

FIG. 15 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to an 8th embodiment of theinvention;

FIG. 16 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 9th embodiment of theinvention;

FIG. 17 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 10th embodiment of theinvention;

FIG. 18 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to an 11th embodiment of theinvention;

FIG. 19 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 12th embodiment of theinvention;

FIG. 20 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 13th embodiment of theinvention:

FIG. 21 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 14th embodiment of theinvention;

FIG. 22 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 15th embodiment of theinvention;

FIG. 23 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 16th embodiment of theinvention;

FIG. 24 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 17th embodiment of theinvention;

FIG. 25 graphically illustrates the principle in the case of extractinga narrow band signal through a narrow band filter from a wide band radiofrequency signal;

FIG. 26 is a block diagram of a velocity detector circuit employed inplace of the velocity detector circuit enclosed in a broken-line frame84 in the 17th embodiment of FIG. 24;

FIG. 27 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to an 18th embodiment of theinvention;

FIG. 28 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 19th embodiment of theinvention;

FIG. 29 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 20th embodiment of theinvention;

FIG. 30 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 21st embodiment of theinvention;

FIG. 31 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 22nd embodiment of theinvention;

FIG. 32 schematically shows a mobile communication system with aplurality of base stations and mobile stations for explaining the 22ndembodiment of FIG. 31;

FIG. 33 schematically shows a mobile communication system with aplurality of base stations and mobile stations for explaining a 23rdembodiment of the invention;

FIG. 34 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 24th embodiment of theinvention;

FIG. 35 shows a TDMA time slot of a signal received by a mobile stationin the 24th embodiment of the invention; and

FIG. 36 is a block diagram showing an internal configuration of avelocity detector circuit 124 employed in the embodiment of FIG. 34.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter a travel velocity detecting apparatus in a mobilecommunication system of the present invention will be described indetail with reference to the accompanying drawings. Referring initiallyto FIGS. 1 through 7, an explanation will be given of the first andsecond principles of the present invention.

To begin with, the first principle will be described below. In themobile communication system, diversity is adopted to cope with fadingwhich is caused by travel of a caller (mobile station). Out of variousmethods of diversity, it is generally customary to employ selectivediversity due to enhanced performance. Here, the first principle will beexplained with regard to an exemplary case employing post-detectionselective diversity.

In a receiver where post-detection selective diversity is realized,there are provided two or more channels of mutually unrelated receivingcircuits (in this example, there are two channels which are termed afirst branch and a second branch). The electric field intensities ofsignals received by such two branches are measured independently of eachother and, after selection of the greater field intensity, the signal ofthe greater intensity received by one of the branches (e.g., secondbranch) is selectively used as a reception output.

The Doppler frequency f_(D), which serves as a parameter to characterizethe fading that represents temporal variations of the received fieldintensity, is expressed as follows by the travel velocity v and thewavelength λ.

    f.sub.D =v/λ

Since the wavelength λ is inherent in the system, its value can beregarded as a fixed wavelength here. Therefore the velocity v can bedetected by finding the frequency f_(D).

In selective diversity, the branch switching frequency is considered tobe on the same order as the Doppler frequency f_(D) which is on avariation scale of the received field intensity. Consequently, under thecondition where the wavelength λ is fixed, the branch switchingfrequency in the selective diversity is considered to be proportional tothe travel velocity v.

Therefore it is possible to calculate the travel velocity v by measuringthe branch switching frequency.

Relative to an exemplary case of incorporating two receiving branches,an explanation will now be given, with reference to FIG. 1, of therelationship between the branch switching frequency and the Dopplerfrequency f_(D) (hence the travel velocity v).

At an instant t shown in FIG. 1, there exists the following numericalrelationship between the power E1(t) received by the first branch andthe power E2(t) received by the second branch. However, it is supposedhere that the received powers E1(t) and E2(t) are so related asrepresented respectively by curves E1 and E2 shown in FIG. 1, and theswitching points thereof are indicated by arrows Y1-YN.

It is also supposed here that a path loss or a distance variation(long-interval median) of a received power and lognormal shadow fading(short-interval median) thereof are common to both the first and secondbranches, and each branch indicates an independent Rayleigh fading(momentary value).

Assuming now that each variation is in a random process, then theprobability of E1(t)>E2(t) is 1/2, and the probability of E1(t)<E2(t) is1/2.

Relative to E1 and E2 obtained at an instant t+Δt, if the value of Δt isso selected that the self-functions of E1 and E2 are rendered zero,E1(t+Δt) and E1(t) are statistically independent of each other, and alsoE2(t+Δt) and E2(t) are statistically independent of each other.

Further with regard to the numerical relationship between E1(t+Δt) andE2(t+Δt), the probability of E1(t+Δt)>E2(t+Δt) is 1/2, and theprobability of E1(t+Δt)<E2(t+Δt) is 1/2.

Suppose here that Δt is equal to τ which is the time interval where theself function of the received wave affected by Rayleigh fading isrendered zero, i.e., the first point 0 of the class-1 Bessel function,in which

    2π·f.sub.D ·τ=2.4

    ∴τ=2.4/(2π·f.sub.D)

Then the number N of times of extracting discrete values of the receivedpower per second is

    N˜1/τ=2π·f.sub.D /2.4=2.6 f.sub.D

Therefore the number of times N_(BC) of switching the first and secondbranches per second is expected as

    N.sub.BC ˜N·P.sub.BC =2.6 f.sub.D /2=1.3 f.sub.D

This theoretical value 1.3 f_(D) is graphically represented by astraight line SL1 in FIG. 2. The result is based on an assumption thatthe correlation between the first and second branches is zero. However,even when there exists a correlation therebetween (except an instancewhere the correlation is completely equal to 1), it is considered thatinformation can be acquired for estimation of the Doppler frequencyf_(D), hence estimation of the travel velocity v.

A straight line SL2 in FIG. 2 represents the experimental value obtainedto ascertain the effects of the present invention by the use of a fadingsimulator (with hard simulation). It is obvious from this result thatthe branch switching frequency is approximately proportional to theDoppler frequency.

Next the second principle of the invention will be explained below. Inthe mobile communication system, Rayleigh fading occurs in accordancewith a travel of a caller (mobile station).

As described in connection with the first principle, the Dopplerfrequency f_(D) that denotes the variation speed of the Rayleigh fadingis expressed as

    f.sub.D =v/λ

In the case of Rayleigh fading, a temporal differential coefficient R'relative to the envelope of a received signal conforms to a Gaussiandistribution where the average value is 0, as shown in FIGS. 3 and 4.

A standard deviation σ denoting the extension of the Gaussiandistribution is expressed as follows and is proportional to the Dopplerfrequency f_(D).

    σ=2πf.sub.D (b.sub.0 /2).sup.1/2

FIG. 3 is a diagram showing a probability density distribution oftemporal differential coefficients R' when the Doppler frequency f_(D)is high, and FIG. 4 is a diagram showing a probability densitydistribution thereof when the Doppler frequency f_(D) is low.

In the above, b₀ denotes the average power of the received signal.Therefore the extension of the probability density distribution, towhich the temporal differential coefficient of the envelope conforms, isproportional to the travel velocity itself. Consequently it becomespossible to estimate the Doppler frequency f_(D) by detecting the amountof dependency of the temporal differential coefficient on the extensionof the probability density distribution, whereby the travel velocity canbe estimated as well.

The amount of variation of the received power level within an extremelyshort time period is proportional to the temporal differentialcoefficient of the envelope. Therefore the amount of variation of thereceived power level is detected at an extremely short time interval,and a calculation is executed to find the probability that the variationamount exceeds a predetermined value. Then the probability thus obtainedis equal to the probability that the temporal differential coefficientexceeds a predetermined value.

This probability is concerned with the extension of the Gaussiandistribution shown in FIGS. 3 and 4. Meanwhile FIGS. 5 and 6 graphicallyshow the temporal variations of the received power level, in which FIG.5 represents the temporal difference of the envelope when the Dopplerfrequency f_(D) is high, and FIG. 6 represents the temporal differencethereof when the Doppler frequency f_(D) is low.

Hereinafter the characteristics of the present invention will bepresumed under the condition that a count is executed every time theenvelope variation exceeds 3 dB (or when the momentary power variationexceeds 6 dB). In the following description, T denotes a radio-wavesampling period, and P₁ and P₂ respectively denote the probability of anincrease and that of a decrease of the envelope by 3 dB during the timeperiod T. ##EQU1##

In the above equations, R(t) denotes the envelope at the instant t, andR'(t)=dR(t)/dt denotes the temporal differential coefficient of theenvelope.

A unit time (1 second) is divided by an extremely short time period Tinto M (=1/T) segments. During such an extremely short time period, thelevel fluctuation is not caused so frequently by the level variations,whereby it can be assumed that the variations are either increasing ordecreasing. In this case, the number of times N_(3dB) of levelvariations over 3 dB per unit time may be written as ##EQU2##

Supposing now that P₁ and P₂ are equal in any time segment mT,

    N.sub.3dB =M (P.sub.1 +P.sub.2)

Since M=f_(s) (where f_(s) denotes the sampling frequency),

    N.sub.3dB =f.sub.s (P.sub.1 +P.sub.2)

With p(R) and p(R') signifying the probability density functions of Rand R' respectively, P₁ and P₂ are expressed as ##EQU3##

Substituting the following specific equations for p(R) and p(R'):

    p(R)=(R/b.sub.0) exp (-R.sub.2 /2b.sub.0)

    p(R')=1/(2πb.sub.2).sup.1/2 exp (-R'.sup.2 /2b.sub.2)

    b.sub.2 =(2πf.sub.D).sup.2 b.sub.0 /2

then N_(3dB) is modified as

    N.sub.3dB =(f.sub.s /2) {1-1/[1+2(2πf.sub.D /f.sub.s).sup.2 ].sup.1/2 }

Thus, it is apparent from the above that N_(3dB) increases in accordancewith f_(D). It is also obvious that N_(3dB) is in the form not includingthe average received power, which has been necessary heretofore in theprior art for measuring the number of times of level zero crossing. InFIG. 7, line segments represent theoretical values of the number N_(3dB)of level variations calculated under the conditions including a maximumDoppler frequency f_(D) of 100 Hz and a sampling frequency f_(s) of 400Hz, and dots represent measured values of N_(3dB) obtained by computersimulation.

It is seen from the above results that the number N_(3dB) of levelvariations is substantially proportional to the Doppler frequency f_(D).

Hereinafter preferred embodiments of the present invention based on theaforementioned first and second principles will be described withreference to the accompanying drawings.

FIG. 8 is a block diagram of a travel velocity detecting apparatus in amobile communication system according to a 1st embodiment of the presentinvention.

The travel velocity detecting apparatus 1 shown in FIG. 8 is installedin a mobile station or a base station (stationary station) of a cartelephone or a portable telephone in a mobile communication system. Inthe relevant station (e.g., mobile station) where the travel velocitydetecting apparatus 1 is installed, the relative travel velocity to theopposite station (e.g., base station) is calculated on the basis ofradio waves received by the relevant station.

The travel velocity detecting apparatus 1 is equipped with two receivingbranches of mutually unrelated channels, wherein there are included afirst receiving circuit 2 of one receiving branch, and a secondreceiving circuit 3 of the other receiving branch. Such two receivingcircuits 2, 3 detect radio communication waves received by antennas 4, 5respectively and, after detection of the received powers, deliver outputpower values E1, E2 therefrom.

Reference numeral 6 denotes a comparator circuit which compares thepower values E1 and E2 with each other and outputs comparison data D1 of"1" when E1>E2 or outputs comparison data D1 of "0" when E1<E2.Meanwhile when E1=E2, the circuit 6 outputs the preceding comparisondata D1.

Reference numeral 7 denotes a variation detector circuit which producesmerely a single pulse signal D2 in response to a change of thecomparison data D1 from "0" to "1" or from "1" to "0".

Denoted by 8 and 9 are a counter and a timer, respectively. The timer 9produces an enable signal D3, which places the counter 8 in an operablestate only for a predetermined time (e.g., 1 second), at a preset orrandom interval during communication. When a pulse signal D2 is inputtedto the counter 8 during supply of an enable signal D3, the counter 8performs one counting operation in response to each input pulse and thenoutputs a count value D4. However, the counter 8 is reset to 0 when anenable signal D3 is supplied thereto.

Reference numeral 10 denotes a converter circuit. This circuit 10 has atable which is composed of count values 0, 1, 2, . . . , N and travelvelocity data assigned correspondingly to such count values. When acount value D4 is inputted, the converter circuit 10 retrieves travelvelocity data D5 corresponding to the count value D4 and then outputsthe retrieved data. The count value D4 corresponds to thereceiving-circuit switching number (branch switching frequency)described in connection with the first principle, and the travelvelocity data assigned correspondingly to the count values arecalculated theoretically according to the first principle or areacquired experimentally.

The conversion by the converter circuit 10 may be executed in compliancewith a program which represents a conversion equation v=(N_(BC) /1.3)·λbased on the theory described in connection with the first principle oranother conversion equation v=(N_(BC) /2.6)¹.2 ·λ based on theexperiment.

The above conversion equation v=(N_(BC) /2.6)¹.2 ·λ based on theexperiment was obtained as follows.

Calculating the relationship between the branch switching frequencyN_(BC) and the Doppler frequency f_(D) on the basis of the experimentalvalue SL2 shown in FIG. 2,

    N.sub.BC =10.sup.0.42 ·f.sub.D.sup.0.85 ≈2.6f.sub.D.sup.0.85

Therefore,

    f.sub.D =(N.sub.BC /2.6).sup.1/0.85 =v/λ

    ∴v=(N.sub.BC /2.6).sup.1/0.85 ·λ≈(n.sub.BC /2.6).sup.1.2 ·λ

According to the travel velocity detecting apparatus 1 of theconstruction mentioned above, first the power values E1, E2 of thereceived radio waves are detected by the first and second receivingcircuits 2, 3, and the power values E1 and E2 are compared with other bythe comparator circuit 6. The data D1 representing the result of suchcomparison, e.g., "1010010110101 . . . ", is inputted to the variationdetector circuit 7 where the variation point is detected. Morespecifically, the number of times of switching the receiving circuits 2and 3 is obtained.

Pulse signals D2 equal in number to the variation points are outputtedfrom the variation detector circuit 7 and then are counted by thecounter 8. If the timer 9 is so preset as to output an enable signal D3only for 1 second, the counter 8 performs its counting operations by thenumber equal to the pulse signals D2 supplied thereto during 1 second,and a count value D4 obtained as a result of such counting operations,i.e., the number of times of switching the receiving circuits 2 and 3,is outputted to the converter circuit 10.

And finally in the converter circuit 10, the travel velocity data D5corresponding to the count value D4 is retrieved and outputted.

According to the travel velocity detecting apparatus 1 of the 1stembodiment described above, it is possible to detect the travel velocityof the mobile station from the received radio communication waves. Andsuch a capability can be realized by a small-scale circuitconfiguration, which is applicable to both a mobile station and a basestation.

Next a travel velocity detecting apparatus 11 of a 2nd embodiment willbe described below with reference to FIG. 9. In the 2nd embodiment shownin FIG. 9, like component circuits corresponding to those used in the1st embodiment are denoted by like reference numerals, and anexplanation thereof is omitted here.

The travel velocity detecting apparatus 11 of the 2nd embodiment shownin FIG. 9 is constructed on the basis of a function to perform apost-detection synthetic diversity and comprises the circuits 2 to 10employed in the 1st embodiment of FIG. 8.

The structural difference from the 1st embodiment resides in that one ofreceived data D6, D7 obtained by first and second receiving circuits 2',3' (diversity branches) is selected in response to comparison data D1,and the data thus selected is outputted as received data D8 which isdelivered to an unshown telephone earpiece.

In this travel velocity detecting apparatus 11 of the 2nd embodimentalso, it is possible to achieve the same effects as those in theaforementioned 1st embodiment.

Now a travel velocity detecting apparatus 14 of a 3rd embodiment will bedescribed with reference to FIG. 10. In the 3rd embodiment of FIG. 10,like component circuits corresponding to those employed in the 1stembodiment of FIG. 8 are denoted by like reference numerals, and anexplanation thereof is omitted here.

The travel velocity detecting apparatus 14 of the 3rd embodiment shownin FIG. 10 is constructed on the basis of a function to perform anantenna switching diversity, wherein electric field intensities of radiowaves received respectively by antennas 4 and 5 of two channels aremeasured within a short time, then the field intensities are comparedwith each other to count the number of times of switching the receivingbranches, and travel velocity data D5 is detected in accordance with thecount value thus obtained.

First the antennas 4 and 5 are switched at a short time interval by aswitching circuit 15 so that input radio waves to the antennas 4 and 5are alternately received.

Then the field intensities e1 and e2 of the radio waves alternatelyreceived are detected by a field intensity detector circuit 16 and areoutputted therefrom. It is supposed here that the field intensity e1signifies the radio waves received by the antenna 4, while the fieldintensity e2 signifies the radio waves received by the antenna 5. It isfurther supposed that the radio waves received by the antenna 4 aredetected first.

In a memory 17, the values of merely the field intensity e1 are storedsuccessively and then are outputted therefrom in the order of suchstorage. The field intensity e1 outputted from the memory 17 and thefield intensity e2 obtained by subsequent switching of the antennas arecompared with each other by a comparator circuit 6' in a next stage.

Comparison data D1 of "1" is outputted when the result of suchcomparison is e1>e2, or comparison data of "0" is outputted when theresult is e1<e2. Meanwhile, when e1=e2, the preceding comparison data D1is outputted.

Thereafter the same process as that described in connection with the 1stembodiment is executed in the circuits posterior to the variationdetector circuit 7, and finally travel velocity data D5 is obtained.Consequently in the travel velocity detecting apparatus 14 of the 3rdembodiment also, it is possible to achieve the same effects as in theaforementioned 1st embodiment.

Next a travel velocity detecting apparatus 19 of a 4th embodiment willbe described below with reference to FIG. 11. In the 4th embodimentshown in FIG. 19, like component circuits corresponding to thoseemployed in the 1st embodiment of FIG. 8 are denoted by like referencenumerals, and an explanation thereof is omitted here.

The travel velocity detecting apparatus 1 of the 4th embodiment shown inFIG. 11 is different from the 1st embodiment in the point that acorrector circuit 20 is provided in a stage posterior to the secondreceiving circuit 3 so as to detect and correct any gain differenceexisting between the first and second receiving circuits 2 and 3.However, the corrector circuit 20 may be provided posterior to the firstreceiving circuit 2 as well.

Such correction of the gain difference is performed for the reason thata proper comparison is not attainable if the power values E1 and E2having any gain difference therebetween are compared with each other bythe comparator circuit 6 without a correction.

According to the 4th embodiment, the aforementioned effects in the 1stembodiment can be similarly achieved, and another advantage can beensured that, despite the existence of any gain difference between thetwo receiving branches, proper travel velocity data D5 is exactlyobtainable by correcting such gain difference.

Next a travel velocity detecting apparatus 22 of a 5th embodiment willbe described below with reference to FIG. 12. In the 5th embodimentshown in FIG. 12, like component circuits corresponding to thoseemployed in the 1st embodiment of FIG. 8 are denoted by like referencenumerals, and an explanation thereof is omitted here.

In comparison with the 1st embodiment, the travel velocity detectingapparatus 22 of the 5th embodiment shown in FIG. 12 has such adifference that a maximum value detector circuit 23 is providedposterior to a converter circuit 10 for detecting the maximum value oftravel velocity data D5.

The maximum value detector circuit 23 compares the input travel velocitydata D5 with the maximum value stored therein and, when the data D5 isgreater than the maximum value, the circuit 23 renews the stored maximumvalue by the data D5 and outputs the same as maximum travel velocitydata D5'.

At the start of communication, such start state is detected and themaximum value is reset. Thereafter the first input travel velocity dataD5 is regarded as a maximum value, and a comparison of such maximumvalue with subsequent input data D5 is executed as mentioned untilcompletion of the communication, whereby the maximum travel velocitydata D5' is detected.

Thus, also in the 5th embodiment having the construction describedabove, the same effects as those in the 1st embodiment can be achievedby extracting the travel velocity data D5 from the output side of theconverter circuit 10, and further the maximum travel velocity data D5'is detectable as well.

The construction of the 5th embodiment may be modified in such a mannerthat the maximum value detector circuit 23 is connected between thecounter 8 and the converter circuit 10 and, instead of the travelvelocity data D5, the maximum of the count value D4 is detected asdescribed. In this case, the maximum of the count value D4 is inputtedto the converter circuit 10 via the maximum value detector circuit 23connected in the modified configuration, so that the travel velocitydata corresponding to the maximum count value is outputted as themaximum travel velocity data D5'.

Since the wavelength λ is determined by each radio wave, if merely asingle frequency band is used practically in the system, the count valueD4 may be converted into the travel velocity data D5 by the convertercircuit 10 employed in the 1st to 5th embodiments mentioned above.

However, in the Japanese car telephone for example where an 800 MHz bandis currently used and another frequency band is permitted to be used ifthe former frequency band is rendered full up to limits, there may occura case where the wavelength λ becomes different even at the same travelvelocity, and consequently the spatial change of the radio waves isrendered different. In this case, proper travel velocity data D5 failsto be obtained by the aforementioned conversion in the converter circuit10.

In such an instance, the construction may be so modified that,differently from any of the 1st to 5th embodiments described above, thewavelength λ (received frequency) is detected by the first or secondreceiving circuit 2 or 3, and the operation of the converter circuit 10is performed in accordance with the detected wavelength λ. Or frequencyinformation of the radio channel to be used is acquired from the systemside and then the operation of the converter circuit 10 is performed inaccordance with such frequency information. However, in the 3rdembodiment of FIG. 10, the construction is so formed that the wavelengthλ is detected by the receiving branch including the switching circuit15.

In a construction where the operation of the converter circuit 10 isperformed by utilizing a table, a plurality of tables are preparedcorrespondingly to individual wavelengths λ to be used forcommunication, and one of the tables is selected in conformity with thewavelength λ detected by the first or second receiving circuit 2 or 3,and subsequently the travel velocity data D5 corresponding to the countvalue D4 is retrieved from the selected table and then is outputted.

In another modified construction where the operation of the convertercircuit 10 is performed by execution of a program which is based on aconversion equation, the wavelength λ included in the equation v=(N_(BC)/1.3)·λ or v=(N_(BC) /2.6)¹.2 ·λ is set to be a variable, and thewavelength λ detected by the first or second receiving circuit 2 or 3 isused as such a variable.

According to the above modified constructions other than those of the1st to 5th embodiments, it is possible to accurately detect propertravel velocity data D5 even if the wavelength λ of the received radiowaves is changed during communication.

Next a travel velocity detecting apparatus 25 of a 6th embodiment willbe described below with reference to a block diagram of FIG. 13.

The travel velocity detecting apparatus 25 of the 6th embodiment shownin FIG. 13 comprises an antenna 26, a receiver 27, a level detectorcircuit 28, a sampling circuit 29, a temporary memory 30, a differencecalculator circuit 31, a threshold memory 32, a comparator circuit 33, atimer 34, a counter circuit 35 and a converter circuit 36.

The receiver 27 detects radio communication waves received by theantenna 26 and produces an output signal.

The level detector circuit 28 serves to detect the level of a signal S1obtained from the receiver 27, and this circuit may consist of, e.g., asignal strength detector.

The sampling circuit 29 samples the received signal level L1, which isoutputted from the level detector circuit 28, at a predeterminedsampling frequency. This sampling circuit 29 generally consists of anA-D converter. Due to the use of an A-D converter, the process to beexecuted in the following stages can be realized in either a digitalform or an analog form.

The temporary memory 30 stores therein the received level data D7obtained from the sampling circuit 29. For this memory 30, a delayelement may be used when storing the data of one sampling period, or anFIFO memory device or the like may be used when a required delay time islonger than one sampling period. Denoted by D8 is the data once storedin the temporary memory 30 and then outputted therefrom.

The difference calculator circuit 31 calculates the difference betweenthe received level data D8 once stored and the current received leveldata D7. This circuit 31 may consist of a code inverter and an adder. Inthe threshold memory 32, a threshold value D10 of a predetermined levelis stored.

The comparator circuit 33 compares the difference data D9 with thethreshold value D10 and produces a pulse signal (comparison result) D11when the difference data D9 is greater than the threshold value D10.

The timer 34 produces an enable signal D12, which places the countercircuit 35 in an operable state only for a preset time (e.g., 1 second),at a predetermined or random interval during communication.

The counter circuit 35 counts, for a preset time, the number of timesthe comparison result D11 obtained from the comparator circuit 33 hasexceeded the threshold value D10. More specifically, when a pulse signalD11 is inputted during supply of an enable signal D12, the circuit 35performs one counting operation in response to each pulse and outputsits count value D13.

The converter circuit 36 converts the relative velocity between therelevant station and the opposite transmitting station from the countresult (count value D13) obtained for the preset time.

For example, the converter circuit 36 has a table which is composed ofcount values 0, 1, 2, . . . , N and travel velocity data assignedcorrespondingly to such count values. When a count value D13 isinputted, the converter circuit 36 retrieves travel velocity data D14corresponding to the count value D13 and then outputs the retrieveddata.

The count value D13 corresponds to the level variation number N_(xdB)having a correlation to the Doppler frequency f_(D) as described inconnection with the second principle, and the travel velocity data D14assigned correspondingly to the count values are calculatedtheoretically according to the second principle or are acquiredexperimentally.

In the travel velocity detecting apparatus 25 of the constructionmentioned, first the radio waves received by the antenna 26 are detectedas a signal S1 in the receiver 27 and, after the level L1 of the signalS1 is detected by the level detector circuit 28, the received signallevel L1 thus detected is sampled by the sampling circuit 29.

Subsequently the sampled level data D7 is once stored in the temporarymemory 30, and the difference between the stored level data D8 and thecurrent received level data D7 is calculated by the differencecalculator circuit 31.

The difference data D9 obtained as a result of such calculation iscompared with the threshold value D19 by the comparator circuit 33, andwhen the difference data D9 is greater than the threshold value D10, apulse signal D11 is outputted from the comparator circuit D11. The pulsesignal D11 is counted by the counter circuit 35 only for the preset timedetermined by the timer 34.

And finally in the converter circuit 36, the travel velocity data D14corresponding to the count value D13 is retrieved and then is outputted.

According to the travel velocity detecting apparatus 25 of the 6thembodiment described above, the travel velocity of a mobile station canbe detected from radio communication waves. And further the apparatus isapplicable to both a mobile station and a base station.

Next a travel velocity detecting apparatus 38 of a 7th embodiment willbe described below with reference to FIG. 14. In the 7th embodiment ofFIG. 14, like component circuits corresponding to those employed in theforegoing 6th embodiment of FIG. 13 are denoted by like referencenumerals, and an explanation thereof is omitted here.

In comparison with the 6th embodiment, the travel velocity detectingapparatus 38 shown in FIG. 14 has a difference in the point that amaximum value detector circuit 39 is provided in a stage posterior tothe converter circuit 36 so as to detect the maximum value of the travelvelocity data D14.

The maximum value detector circuit 39 is reset at the start of eachcommunication for example and, when the travel velocity obtained at afixed time interval is greater than the preceding maximum value,functions to hold and output such travel velocity as a new maximumvalue. More specifically, according to this function, the input travelvelocity data D14 is compared with the maximum value stored in thecircuit 39, and when the data D14 is greater than the stored maximumvalue, the data D14 is held as a renewed maximum value while beingoutputted as maximum travel velocity data D14'. This function can berealized with facility by a combination of a comparator and a latchcircuit.

In the above construction also, it is possible to achieve the sameeffects as those in the 6th embodiment by acquiring the travel velocitydata D14 from the output side of the converter circuit 36. And furtherthe maximum travel velocity data D14' can be detected as well.

Next a travel velocity detecting apparatus 41 of an 8th embodiment willbe described with reference to FIG. 15. In the 8th embodiment shown inFIG. 15, like component circuits corresponding to those employed in theaforementioned 1st embodiment of FIG. 8 are denoted by like referencenumerals, and an explanation thereof is omitted here.

The travel velocity detecting apparatus 41 of the 8th embodiment shownin FIG. 15 is installed in a mobile station of a car telephone or aportable telephone in a mobile communication system and is capable ofdetecting the received level of radio communications waves, which aretransmitted thereto from a base station, adaptively in accordance withthe travel velocity of the relevant mobile station.

The travel velocity detecting apparatus 41 is equipped with tworeceiving branches of mutually unrelated channels, wherein there areincluded a first receiving circuit 42 of one receiving branch, and asecond receiving circuit 43 of the other receiving branch. Such tworeceiving circuits 42, 43 detect radio communication waves received byantennas 44, 45 respectively and, after detection of the received levelsE1, E2, deliver the levels as outputs therefrom.

Reference numeral 46 denotes a comparator circuit which compares thereceived levels E1 and E2 with each other and outputs comparison dataD16 of "1" when E1>E2 or outputs comparison data D16 of "0" when E1<E2.Meanwhile when E1=E2, the comparator circuit 46 outputs the precedingcomparison data D16.

Reference numeral 47 denotes a variation detector circuit which producesmerely a single pulse signal D17 in response to a change of thecomparison data D16 from "0" to "1" or from "1" to "0".

Denoted by 48 is a counter circuit. This counter circuit 48 performs onecounting operation in response to each pulse of the pulse signal D17 andcounts up when the count value thereof has reached a preset value,thereby outputting a count-up signal D18 of a single pulse. In thiscase, the count value of the counter circuit 48 corresponds to thereceiving-circuit switching number (branch switching frequency)described in connection with the first principle.

Denoted by 49 is an averaging circuit. During the time period from aninitial state to input of a count-up signal D18, the averaging circuit49 executes a temporal averaging process of the received levels E1 fedfrom the first receiving circuit 42 and then outputs the resultantaverage value as an average received level EM. The averaging circuit 49is reset to be initialized immediately after outputting the averagereceived level EM, and then resumes its calculation of averaging thereceived levels E1.

According to the travel velocity detecting apparatus 41 of theconstruction described above, the received levels E1, E2 of radiocommunication waves are detected by the first and second receivingcircuits 42, 43, and then such levels E1 and E2 are compared with otherby the comparator circuit 46.

Subsequently, comparison data D11 such as "1010010110101 . . . "obtained as a result of the comparison is inputted to a variationdetector circuit 47, where the variation points are detected. In otherwords, the number of times of switching the receiving circuits 42 and 43is obtained in this circuit 47.

Pulse signals D17 equal in number to the variation points are outputtedfrom the variation detector circuit 47 and then are counted by a countercircuit 48.

It is assumed here that the counter circuit 48 is so preset as toperform its count-up operation at a count value 50.

When the count value has reached 50, a count-up signal D18 is suppliedto the averaging circuit 49, from which the average value of thereceived levels E1 is outputted as an average received level EM.

In the travel velocity detecting apparatus 41 of the 8th embodimentdescribed above, the received levels are detected in conformity with thenumber of times of switching the receiving circuits 42 and 43, so thatthe received levels are accurately detectable regardless of the travelvelocity of the mobile station. Consequently, the received level can bedetected adaptively to the travel velocity of the mobile station.

Furthermore, due to the nonnecessity of calculating the travel velocitydifferently from the prior art, the travel velocity estimation meansrequired heretofore in the conventional apparatus is no longer needed toeventually attain a dimensional reduction of the whole apparatus.

Next a travel velocity detecting apparatus 51 of a 9th embodiment willbe described below with reference to FIG. 16. In the 9th embodiment ofFIG. 16, like component circuits corresponding to those employed in the8th embodiment of FIG. 15 are denoted by like reference numerals, and anexplanation thereof is omitted here.

The travel velocity detecting apparatus 51 of the 9th embodiment shownin FIG. 16 comprises the circuits of the foregoing 8th embodiment shownin FIG. 15 with another function to perform a post-detection syntheticdiversity.

In particular, the difference from the 8th embodiment resides in thatone of the received data D18 and D20 obtained respectively from firstand second receiving circuits 42' and 43', which serve as diversitybranches, is selected in accordance with comparison data D16, and theselected data D19 (or D20) is outputted as received data D21 which isdelivered to an unshown telephone earpiece.

The effects achieved in the travel velocity detecting apparatus 51 ofthe 9th embodiment is similar to those in the foregoing 8th embodiment.

Next a travel velocity detecting apparatus 54 of a 10th embodiment willbe described below with reference to FIG. 17. In the 10th embodiment ofFIG. 17, like component circuits corresponding to those employed in the8th embodiment of FIG. 15 are denoted by like reference numerals, and anexplanation thereof is omitted here.

The travel velocity detecting apparatus 54 of the 10th embodiment shownin FIG. 17 is equipped with a function to perform an antenna switchingdiversity. In this apparatus, electric field intensities of radio wavesreceived by antennas 44 and 45 of two channels are measured within ashort time period and then are compared with each other. Subsequentlythe number of times of switching the receiving branches is counted, andthe average received level EM is detected on the basis of the countvalue.

First the antennas 44 and 45 are switched in a short time period bymeans of a switching circuit 55, so that radio waves fed to the antennas44 and 45 are alternately received.

Subsequently the electric field intensities e1 and e2 of the radio wavesalternately received are detected by and outputted from a fieldintensity detector circuit 56. It is defined here that the fieldintensity e1 indicates the radio waves received by the antenna 44, whilethe field intensity e2 indicates the radio waves received by the antenna45, and also that the intensity of the radio waves received by theantenna 44 is detected first.

The detected field intensities e1 are successively stored in a memory 57and then are outputted therefrom. In a comparator circuit 46' of aposterior stage, the field intensity e1 outputted from the memory 57 iscompared with the field intensity e2 obtained by a subsequent antennaswitching operation. The circuit 46 produces comparison data D16 of "1"when the comparison result signifies e1>e2, or produces comparison dataD16 of "0" when the result signifies e1<e2. Meanwhile, when e1=e2, thepreceding comparison data D16 is outputted.

Thereafter the process explained in connection with the 8th embodimentis executed in the circuits posterior to the variation detector circuit47, and finally an average received level EM is obtained. Consequentlythe effects similar to those of the 8th embodiment are achievable alsoin the travel velocity detecting apparatus 54 of the 10th embodiment.

In the same procedure as the above, similar effects can be achieved byinputting the field intensity e2 to the averaging circuit 49 in FIG. 17.

Next a travel velocity detecting apparatus 59 of an 11th embodiment willbe described below with reference to FIG. 18. In the 11th embodiment ofFIG. 18, like component circuits corresponding to those employed in the8th embodiment of FIG. 15 are denoted by like reference numerals, and anexplanation thereof is omitted here.

In the travel velocity detecting apparatus 59 of the 11th embodimentshown in FIG. 18, the difference from the 8th embodiment resides in thata corrector circuit 60 is provided in a stage posterior to the secondreceiving circuit 43 so as to detect and correct any gain differencethat may exist between the first and second receiving circuits 42 and43. However, the corrector circuit 60 may be provided in a stageposterior to the first receiving circuit 42.

Such correction of the gain difference is needed for the reason that aproper comparison fails to be performed in case the received levels E1and E2 having any gain difference therebetween are compared with eachother by the comparator circuit 46.

According to the 11th embodiment mentioned, the same effects areachievable as in the 8th embodiment and, even when any gain differenceis existent between the two receiving branches, the average receivedlevel EM can be properly obtained by correcting such a gain difference.

In addition, the same effects are also achieved by inputting the levelE2' to the averaging circuit 49 in FIG. 18.

Next a travel velocity detecting apparatus 62 of a 12th embodiment willbe described below with reference to FIG. 19. In the 12th embodiment ofFIG. 19, like component circuits corresponding to those employed in the8th embodiment of FIG. 15 are denoted by like reference numerals, and anexplanation thereof is omitted here.

In comparison with the aforementioned 8th embodiment, the travelvelocity detecting apparatus 62 of the 12th embodiment shown in FIG. 19has a difference in the point that a higher one of the received levelsE1 and E2 is selected by means of a selector circuit 63, and theselected level E3 is temporally averaged.

More specifically, when the output data D16 of the comparator circuit 46signifies that the received level E2 is higher, the level E2 is selectedby the selector circuit 63 and then is outputted to the averagingcircuit 49. Meanwhile, when the data D16 signifies that the receivedlevel E1 is higher, the level E1 is selected by the selector circuit 63and then is outputted to the averaging circuit 49.

In the averaging circuit 49, therefore, the higher received level E1 orE2 is temporally averaged to consequently attain an advantage that theaverage received level EM obtainable in this embodiment is higher ingain than the level in any of the embodiments mentioned heretofore. Theother effects are similar to those in the 8th embodiment.

Next a travel velocity detecting apparatus 65 of a 13th embodiment willbe described below with reference to FIG. 20. In the 13th embodiment ofFIG. 20, like component circuits corresponding to those employed in the8th embodiment of FIG. 15 are denoted by like reference numerals, and anexplanation thereof is omitted here.

The travel velocity detecting apparatus 65 of the 13th embodiment shownin FIG. 20 is characterized in its constitution where sample values ofthe received level E1 or E2 are partially excluded from the temporalaveraging in accordance with the switching frequency of receivingcircuits 42 and 43.

An averaging circuit 49' is supplied with output data D17 of a variationdetector circuit 47 which indicates a variation in the numericalrelationship between the received levels E1 and E2, wherein the receivedlevel E1 is temporally averaged only during a supply of the data D17.

More specifically, a sample value of the received level E1, which isobtained in the absence of a variation in the numerical relationshipbetween the received levels E1 and E2, is excluded from the temporalaveraging. Thus, the averaging operation is performed merely by the useof statistically effective sample values, hence reducing the circuitscale inclusive of an integrator required for the averaging. The othereffects are the same as those in the aforementioned 8th embodiment.

Next a travel velocity detecting apparatus 67 of a 14th embodiment willbe described below with reference to FIG. 21. In the 14th embodiment ofFIG. 21, like component circuits corresponding to those employed in the8th embodiment of FIG. 15 are denoted by like reference numerals, and anexplanation thereof is omitted here.

The travel velocity detecting apparatus 67 of the 14th embodiment shownin FIG. 21 is characterized in its constitution where the received-levelsampling frequency is controlled in accordance with the switchingfrequency of receiving circuits 42 and 43.

In FIG. 21, there are shown a second comparator circuit 68, a samplingclock source 69, a second counter circuit 70, and a 1/N circuit 71.

The sampling clock source 69 delivers an operation clock signal CK tothe circuits indicated by broken lines. The frequency of the operationclock signal CK is changed in accordance with the output data D21 of thesecond comparator circuit 68.

The second counter circuit 70 counts the frequency of the operationclock signal CK, and the 1/N circuit 71 divides the count value D19 ofthe second counter circuit 70 into 1/N and then outputs the dividedvalue.

It is defined here that 1/N is set to a value smaller than 1/2, e.g., to1/3.

The second comparator circuit 68 compares data D11, which is 1/3 of thecount value D19, with data D18 indicative of the branch switchingfrequency, and produces output data D21 which represents the differencebetween the compared data D20 and D18.

In the travel velocity detecting apparatus 67 of the above-describedconstruction, the following operation is performed. The data D18 and D20are compared with each other by the second comparator circuit 68. And ifthe result signifies that the branch switching frequency is greater than1/3 of the count value of the operation clock signal CK, the samplingclock source 69 is so controlled as to raise the frequency of theoperation clock signal CK.

Meanwhile, if the branch switching frequency is smaller than 1/3 of thecount of the operation clock signal CK, the sampling clock source 69 isso controlled as to lower the frequency of the operation clock signalCK.

Such control action is executed for the following reason. When thesampling frequency is low and the individual sample values of thereceived levels E1 and E2 are statistically independent, the branchswitching frequency is exactly equal to 1/2 of the sampling frequency.Therefore the sampling frequency is so adjusted as to render the branchswitching frequency slightly lower than 1/2 of the sampling frequency.

The branch switching points can be caught more precisely if the rate ofsampling the received levels E1 and E2 is increased by raising thesampling frequency. In such a case, however, the circuits are morecomplicated and enlarged in scale. Therefore the construction isadequately formed in such a manner as to ensure a practically highprobability of catching the switching points while simplifying thecircuit configuration and suppressing the same to a small scale.

According to the 14th embodiment described above, it is possible todetect the received level adaptively to the travel velocity of themobile station and is further possible to realize a small-scale circuitconfiguration.

Next a travel velocity detecting apparatus 73 of a 15th embodiment willbe described below with reference to FIG. 22. In the 15th embodiment ofFIG. 22, like component circuits corresponding to those employed in the1st embodiment of FIG. 8 are denoted by like reference numerals, and anexplanation thereof is omitted here.

In comparison with the 1st embodiment, the travel velocity detectingapparatus 73 shown in FIG. 22 has a difference in the point that anintegrator circuit 74 for integrating travel velocity data D5 isprovided in a stage posterior to the converter circuit 10. Suchintegration of the travel velocity data D5 is executed for the purposeof calculating the travel distance of the mobile station.

More specifically, with regard to the travel velocity (speed) v(t) at aninstant t, a passage distance 1(t) from an instant 0 is obtained byintegrating the travel velocity v(t) as expressed below. ##EQU4## wherean instant 0 signifies a communication start time.

As a result, data D23 indicating the travel distance of the mobilestation is outputted from the integrator circuit 74.

Consequently, according to the 15th embodiment, the travel distance ofthe mobile station during communication can be obtained from the passagedistance data D23.

Next a travel velocity detecting apparatus 76 of a 16th embodiment willbe described below with reference to FIG. 23. In the 16th embodiment ofFIG. 23, like component circuits corresponding to those employed in the1st embodiment of FIG. 8 are denoted by like reference numerals, and anexplanation thereof is omitted here.

In comparison with the 1st embodiment, the travel velocity detectingapparatus 76 of the 16th embodiment shown in FIG. 23 has a difference inthe point that a differentiator circuit 77 for differentiating thetravel velocity data D5 is provided in a stage posterior to theconverter circuit 10. Such differentiation of the travel velocity dataD5 is executed for the purpose of calculating the acceleration of themobile station.

More specifically, the acceleration a(t) representing the change rate ofthe travel velocity can be obtained by differentiating the travelvelocity v(t) as follows.

    a(t)=dv(t)/dt

As a result, data D22 indicating the acceleration of the mobile stationis outputted from the differentiator circuit 77.

Consequently, according to the 16th embodiment, the acceleration of themobile station can be obtained from the acceleration data D25.

Next a travel velocity detecting apparatus 79 of a 17th embodiment willbe described below with reference to FIG. 24. In the 17th embodiment ofFIG. 24, like component circuits corresponding to those employed in the6th embodiment of FIG. 13 are denoted by like reference numerals, and anexplanation thereof is omitted here.

The travel velocity detecting apparatus 79 shown in FIG. 24 detects thetravel velocity by receiving a wide-band radio signal S10. Each of the1st to 15th embodiments mentioned hereinabove is a type which receivesnarrow-band radio waves for the reason of utilizing the Rayleigh fadingthat occurs when the radio waves are in a narrow band, as explained inconnection with the first and second principles.

However, in wide-band radio transmission as shown in FIG. 25, there isobserved a phenomenon termed frequency selective fading where levelvariations are caused nonuniformly over the entire transmissionbandwidth B_(w), and the received levels are different depending on theindividual frequencies as indicated by a curve 80.

In the case of such frequency selective fading, level variations arecaused in the input signal power of the entire band and are thereforedifferent from those in the Rayleigh fading.

In other words, a variety of level variation patterns are induced incompliance with an extension of the transmission bandwidth B_(w), sothat it is impossible to calculate the travel velocity, on the basis ofthe first and second principles, from the received level variations inthe wide-band radio signal S10.

However, if the bandwidth of the wide-band radio signal S10 is limitedby means of, e.g., a filter of a narrow bandwidth (denoted by B_(N1) orB_(N2) in FIG. 25), the Rayleigh fading can be utilized for thenarrow-band signal obtained by the above means. Therefore it becomespossible to calculate the travel velocity on the basis of the first andsecond principles.

The travel velocity detecting apparatus 79 shown in FIG. 24 isconstructed on the basis of the theory mentioned, wherein theabove-described narrow band filter is connected between the receiver 27and the level detector circuit 28 employed in the travel velocitydetecting apparatus 25 of the 6th embodiment shown in FIG. 13. However,the aforementioned receiver 27 is replaced here with a receiver 82 whichis capable of detecting the wide-band radio signal S10 shown in FIG. 24.

According to the travel velocity detecting apparatus 79 of suchconstruction, first the radio waves received by an antenna 81 aredetected in the receiver 82. And the bandwidth of a wide-band signal S11obtained through the detection is limited by means of the narrow-bandfilter 83, whereby a narrow-band signal S12 is produced.

The level L1 of the narrow-band signal S12 is detected by a leveldetector circuit 28, and the received level L1 thus detected is sampledby a sampling circuit 29. The data D7 representing the sampled level isonce stored in a temporary memory 30, and the difference between thestored level data D8 and the current received level data D7 iscalculated in a difference calculator circuit 31.

The difference data D9 obtained as a result of such calculation iscompared with the threshold value D10 by a comparator circuit 33 and,when the difference data D9 is greater than the threshold value D10, apulse signal D11 is outputted from the comparator circuit 33. Then thepulse signal D11 is counted by a counter circuit 35 only during a presettime determined by a timer 34.

Finally the travel velocity data D14 corresponding to the count valueD13 is retrieved and outputted from a converter circuit 36. The velocitydetector circuit enclosed in a broken-line frame 84 in the travelvelocity detecting apparatus 79 may be replaced with a velocity detectorcircuit 86 shown in FIG. 26.

The velocity detector circuit 84 detects the velocity by calculating thereceived level difference, whereas the velocity detector circuit 86performs its operation by detecting the number of received levelcrossings.

As shown in FIG. 26, the velocity detector circuit 86 comprises anaveraging circuit 85, a comparator circuit 33, a timer 34, a countercircuit 35 and a converter circuit 36. It is defined here that theaveraging circuit 85 is functionally similar to the aforementionedaveraging circuit 49 shown in FIG. 15. And like component elementscorresponding to those employed in the velocity detector circuit 84 ofFIG. 24 are denoted by like reference numerals.

In the construction described above, the average value of the receivedlevel L1 detected by the level detector circuit 28 is calculated by theaveraging circuit 85, and the result is outputted therefrom as anaverage level L2.

Thereafter the average level L2 and the received level L1 are comparedwith each other by the comparator circuit 33 and, when the receivedlevel L1 exceeds the average level L2, a pulse signal D11 is outputtedfrom the comparator circuit 33. The pulse signal D11 is counted by thecounter circuit 35 only during a preset time determined by the timer 34,and the travel velocity data D14 corresponding to the count value D13 isobtained in the converter circuit 36.

According to the 17th embodiment mentioned above, the travel velocity ofa mobile station can be detected from a wide-band radio signal as well.

Next a travel velocity detecting apparatus 88 of an 18th embodiment willbe described below with reference to FIG. 27. In the 18th embodiment ofFIG. 27, like component circuits corresponding to those employed in the17th embodiment of FIG. 24 are denoted by like reference numerals, andan explanation thereof is omitted here.

The travel velocity detecting apparatus 88 shown in FIG. 27 ischaracterized in its construction including first and second narrow-bandfilters 83 and 83' whose center frequencies are spaced apart from eachother by a predetermined bandwidth, wherein two narrow-band signals S12and S13 can be obtained from a wide-band radio signal S10.

The reason for forming such a construction will now be explained withreference to FIG. 25. In the frequency selective fading, a frequencyinterval (correlation bandwidth B_(c) shown in FIG. 25), where thereoccurs none of frequency correlation between level variations, i.e.,correlation between level variations at different frequencies, is saidto be 640 kHz in an 800 MHz band for example.

Therefore, when the transmission bandwidth B_(w) is sufficiently widerthan a frequency interval of 640 kHz, the circuit configuration may beso arranged that the respective center frequencies .sub.Δ f ofnarrow-band filters are spaced apart from each other by a frequencyinterval greater than the correlation bandwidth Bc, whereby it isrendered possible to obtain a plurality of mutually independent receivedlevels based on the Rayleigh fading.

According to the travel velocity detecting apparatus 88 shown in FIG.27, a wide-band signal S11 obtained by detection in the receiver 82 ispassed through the first and second narrow-band filters 83 and 83'.

Consequently, narrow-band signals S12 and S13 of mutually differentbands are outputted from the first and second narrow-band filters 83 and83' respectively.

The levels L1 and L3 of the narrow-band signals S12 and S13 are detectedby first and second level detector circuits 28 and 28' respectively.

The two received levels L1 and L3 thus detected are compared with eachother by a comparator circuit 33, and comparison data D11 of, e.g., "1"is outputted when the level L1 is higher. The comparison data is "0"when the level L3 is lower, or the preceding numerical value isoutputted when the compared levels are equal to each other.

The comparison data D11 is inputted to a variation detector circuit 89and, upon detection of a variation point, a pulse signal D27 isoutputted therefrom. The pulse signal D27 is then counted by a countercircuit 35 during a preset time determined by a timer 34, and the travelvelocity data D14 corresponding to the count value D13 is retrieved byand outputted from a converter circuit 36.

Also in the 18th embodiment explained above, it is possible to achievethe same effects as those in the aforementioned 17th embodiment.

Next a travel velocity detecting apparatus 92 of a 19th embodiment willbe described below with reference to FIG. 28. In the 19th embodiment ofFIG. 28, like component circuits corresponding to those in the foregoing18th embodiment of FIG. 27 are denoted by like reference numerals, andan explanation thereof is omitted here.

The travel velocity detecting apparatus 92 shown in FIG. 28 ischaracterized in its construction where a plurality of narrow-bandfilters are included, and the maximum value out of travel velocity dataobtained via a plurality of branches relative to such filters isdetected and outputted. However, similarly to FIG. 27, only two branchesrelative to first and second narrow-band filters 83 and 83' are shown inFIG. 28. And velocity detector circuits 93 and 93' each for detectingthe velocity in the individual branch are connected to stages posteriorto first and second level detector circuits 28 and 28'.

Each of the velocity detector circuits 93 and 93' may be composed of theaforementioned velocity detector circuit denoted by a broken-line frame84 in FIG. 24 or the velocity detector circuit 86 shown in FIG. 26.

According to the above construction, travel velocity data D14 and D14'are detected in the individual branches relative to the narrow-bandfilters 83 and 83' respectively, and the maximum value (e.g., D14) ofthe entire travel velocity data is detected by a maximum value detectorcircuit 94 and then is outputted therefrom as travel velocity data D29.

Thus, according to the 19th embodiment mentioned above, one travelvelocity indicative of the maximum value can be detected out of aplurality of travel velocities detected from a plurality of frequencybands.

Next a travel velocity detecting apparatus 95 of a 20th embodiment willbe described below with reference to FIG. 29. In the 20th embodiment ofFIG. 29, like component circuits corresponding to those employed in theforegoing 19th embodiment of FIG. 28 are denoted by like referencenumerals, and an explanation thereof is omitted here.

In comparison with the 19th embodiment of FIG. 28, the travel velocitydetecting apparatus 95 shown in FIG. 29 has a difference in the pointthat the aforementioned velocity detector circuit denoted by abroken-line frame 90 in FIG. 27 is applied to velocity detector circuits96 and 96', and levels L1 and L3 detected by different level detectorcircuits 28 and 28' are inputted to a comparator circuit 33 which isincluded in the velocity detector circuit 90.

Also in the 20th embodiment of the construction mentioned above, it ispossible to achieve the same effects as those in the foregoing 19thembodiment.

Next a travel velocity detecting apparatus 98 of a 21st embodiment willbe described below with reference to FIG. 30. In the 21st embodiment ofFIG. 30, like component circuits corresponding to those employed in the17th embodiment of FIG. 24 are denoted by like reference numerals, andan explanation thereof is omitted here.

The travel velocity detecting apparatus 98 shown in FIG. 30 is installedin a mobile station in a CDMA (code division multiple access) system anddetects the travel velocity by receiving a wide-band radio signal S10 asin the aforementioned 17th embodiment.

Reference numeral 99 in FIG. 30 denotes an inverse diffusion circuitwhich multiplies the same code as the one superimposed by a diffusioncircuit on the transmission side, thereby reproducing a transmittedsignal S15.

Denoted by 100 is a demodulator circuit which converts the signal S15into digital data D31. A velocity detector circuit 84 in FIG. 30 may bereplaced with the aforementioned velocity detector circuit 86 shown inFIG. 26.

Since the travel velocity detecting apparatus 98 of the 21st embodimentrepresents an exemplary application to a CDMA system, it is impossibleto detect the relative travel velocity to a base station, and thereforethe apparatus 98 detects merely the travel velocity of the mobilestation alone.

Next a travel velocity detecting apparatus 102 of a 22nd embodiment willbe described below with reference to FIG. 31.

The travel velocity detecting apparatus 102 shown in FIG. 31 isinstalled in a mobile station and is capable of detecting the travelvelocity thereof further precisely by first receiving radio waves ofmutually different frequencies simultaneously from three base stations,then detecting the travel velocities on the basis of the individualreceived radio waves, and selecting the maximum value of the detectedtravel velocities.

An explanation will now be given with regard to the principle in anexemplary case of calculating the travel velocity v by detecting aquantity which is in a proportional or monotone increasing relation tothe Doppler frequency f_(D). Relative to an angle θ formed by theforward direction of the mobile station (travel velocity vector) and theincoming direction of power-wise dominant radio waves out of the entirereceived radio waves, a level-variation dominant component is expressedas f_(D) cos θ, so that the estimated travel velocity is expressed as vcos θ. Since the angle θ changes every moment, it is usual to observethe angle θ for a long time or to observe a plurality of estimatedtravel velocities v cos θ where each θ is independent, hence realizing afurther precise calculation of the travel velocity v by adopting themaximum value (cos θ≈1).

The travel velocity detecting apparatus 102 of FIG. 31 constituted onthe basis of the above principle comprises an antenna 103, a hybridcircuit 104, receivers 105, 106 and 107, velocity detector circuits 108,109 and 110, and a synthesizer circuit 111.

FIG. 32 shows a mobile station 113 where the travel velocity detectingapparatus 102 is installed, and also shows three base stations 114, 115and 116 located at mutually different sites. It is supposed here thatthe mobile station 113 communicates with the base stations 114, 115 and116 by the use of radio signals S21, S22 and S23 having mutuallydifferent frequencies f1, f2 and f3 respectively.

In this example, it is assumed now that the mobile station iscommunicating with the base station 114 as indicated by a bidirectionalarrow line 117. And the travel velocity vector of the mobile station 113is represented by an arrow line 118.

When the mobile station 113 detects its travel velocity, the travelvelocity detecting apparatus 102 installed therein simultaneouslyreceives three radio signals S21-S23 (hereinafter expressed collectivelyas S20) of three different frequencies f1-f3.

In the travel velocity detecting apparatus 102, the antenna 103 receivesthe three radio signals S24.

The received signals S24 are branched into three by the hybrid circuit104. And the individual signals S25 thus branched are inputted to thereceivers 105, 106 and 107 respectively.

The receiver 105 demodulates the signal S26 (component of radio signalS21) of the frequency f1 from the input signal S25; the receiver 106demodulates the signal S27 (component of radio signal S22) of thefrequency f2 from the input signal S25; and the receiver 107 demodulatesthe signal S28 (component of radio signal S23) of the frequency f3 fromthe input signal S25.

The signals S26, S27 and S28 thus obtained are inputted to the velocitydetector circuits 108, 109 and 110 respectively.

In the velocity detector circuits 108-110, relative travel velocitiesD41, D42 and D43 to the base stations 114-116 are detected from theinput signals S26-S28 and are outputted.

The internal circuit configuration of each of the velocity detectorcircuits 108-110 is the same as that of, e.g., FIG. 13 including fromthe level detector circuit 28 to the converter circuit 36.

The synthesizer circuit 111 shown in FIG. 31 selects the maximum valueout of the three travel velocities D41-D43 inputted thereto and thenoutputs the selected maximum value as a travel velocity D44 finallyobtained.

According to the travel velocity detecting apparatus 102 of the 22ndembodiment mentioned above, it is possible to attain a high precision indetecting the travel velocity of the mobile station.

Next a travel velocity detecting apparatus of a 23rd embodiment will bedescribed below with reference to FIG. 33. In the 23rd embodiment ofFIG. 33, like component circuits corresponding to those in FIG. 32 aredenoted by like reference numerals, and an explanation thereof isomitted here.

In the 23rd embodiment, the velocity detector circuit 108 of the travelvelocity detecting apparatus 102 shown in FIG. 31 is installed in eachof base stations 114-116, and the synthesizer circuit 111 in FIG. 31 isinstalled in a network control station 119.

The operation in FIG. 33 is performed in the following manner. Inresponse to a command from the network control station 119, the basestations 115 and 116 not concerned in a communication receive a radiosignal S28 outputted from a mobile station 113, then estimate therelative travel velocities D46 and D47 between the mobile station 113and the relevant station (base station), and send such travel velocitiesD46 and D47 to the network control station 119.

The synthesizer circuit 111 in the network control station 119 selects agreater value out of the two input travel velocities D46 and D47, andthen outputs the selected value as the travel velocity of the mobilestation 113 finally obtained. The synthesizer circuit 111 may beinstalled in each of the base stations 114-116. In this case, however,it becomes necessary to transfer the travel velocities D46 and D47,which are estimated in the other base stations 115 and 116, via thenetwork control station 119 or an unshown exchange to the relevant basestation (114 in this example) concerned in the communication.

Also in the 23rd embodiment mentioned above, a high precision isattainable in detecting the travel velocity of the mobile station, as inthe foregoing 22nd embodiment.

Next a travel velocity detecting apparatus 120 of a 24th embodiment willbe described below with reference to FIG. 34.

The travel velocity detecting apparatus 120 shown in FIG. 34 isapplicable to a TDMA (time division multiple access) mobilecommunication system. The system constitution relative to base stationsand a mobile station is the same as that in FIG. 32.

In this system, as shown in FIG. 35, a TDMA frame 130 is multiplexed bytime division in accordance with the number of first to third radiosignals S21-S23 transmitted from base stations 114-116. In this example,the number of multiplexed signals is three. A mobile station 113receives a signal S21 of a frequency f1 through a first time slot 131 inthe frame 130, a signal S22 of a frequency f2 through a second time slot132, and a signal S23 of a frequency f3 through a third time slot 133,respectively. And the travel velocity is calculated from each of thesignals S21 to S23 received successively.

In FIG. 34, there are included an antenna 121, a receiver 122, a TDMAcontroller 123, a velocity detector circuit 124, and a synthesizercircuit 125.

The receiver 122 receives the radio signals S21-S23 successively undercontrol of the TDMA controller 123 and demodulates the received signals.The TDMA controller 123 supplies first, second and third control signalsS31, S32 and S33 to the receiver 122 for a fixed time period cyclicallyso as to enable the receiver 122 to receive the signals S21-S23 of thefrequencies f1-f3 in succession. More specifically, the signal S21 isreceived during supply of the first control signal S31 to the receiver122, and the signal S22 is received during supply of the second controlsignal S32 to the receiver 122, and the signal S23 is received duringsupply of the third control signal S33 to the receiver 122.

The velocity detector circuit 124 detects three travel velocities fromfirst, second and third demodulated signals S34, S35 and S36 outputtedsuccessively from the receiver 122. It is defined here that the first,second and third demodulated signals S34, S35 and S36 are obtained bydemodulating the first, second and third radio signals S21, S22 and S23,respectively.

The velocity detector circuit 124 will now be described in detail withreference to a block diagram of FIG. 36 which shows its internalconfiguration.

A level detector circuit 140 detects the levels of the first to thirddemodulated signals S34-S36. Then a sampling circuit 141 samples thefirst, second and third levels L11, L12 and L13, which are obtained fromthe level detector circuit 141, at a predetermined sampling frequency.The sampling circuit 141 is normally composed of an A-D converter. Dueto the use of an A-D converter, the succeeding process can be digitallyexecuted.

A temporary memory 142 successively stores first, second and third leveldata D51, D52 and D53 obtained from the sampling circuit 29 and thenoutputs such data in the order of the storage. The data once stored inthe memory 142 and subsequently outputted therefrom are termed herefirst, second and third storage data D54, D55 and D56.

A difference calculator circuit 143 calculates the respectivedifferences between the first to third storage data D54, D55, D56 andthe first to third level data D51, D52, D53, and outputs first to thirddifference data D57, D58, D59 therefrom.

A threshold memory 144 stores a threshold value D60 of a predeterminedlevel. A comparator circuit 145 compares each of the first to thirddifference data D57, D58, D59 with the threshold value D60, and when thedifference data D57, D58, D59 exceed the threshold value D60, thecomparator circuit 145 outputs first to third pulse signals D61, D62,D63 therefrom.

A timer 147 produces first to third enable signals S38, S39, S40, whichplace first to third counter circuits 148, 149, 150 in an operable staterespectively, in response to supply of the first to third controlsignals S31, S32, S33 outputted from the TDMA controller 123.

More specifically, the first enable signal S38 is outputted from thetimer 147 during supply of the first control signal S31, and the secondenable signal S39 is outputted during supply of the second controlsignal S32, and the third enable signal S40 is outputted during supplyof the third control signal S33.

First to third counter circuits 148, 149, 150 respectively count firstto third pulse signals D61, D62, D63 only for a time during which thefirst to third enable signals S38, S39, S40 are supplied thereto. Andupon completion of repeated supply of the first to third enable signalsS38, S39, S40 a predetermined number of times, the counter circuits 148,149, 150 output first to third count values D64, D65, D66 and then arereset. The counting operation is so performed as to count one per pulseof the input signals (D61, D62, D63).

The first enable signal S38 and the first pulse signal D61, both ofwhich result from the first control signal S31, are suppliedsimultaneously to the first counter circuit 148. And such timingrelation is the same with respect to the other signals as well.

More specifically, in response to the first enable signal S38 suppliedto the first counter circuit 148, this circuit 148 counts the inputfirst pulse signal D61 during the enable-signal supply time. Meanwhilein response to the second enable signal S39 supplied to the secondcounter circuit 149, this circuit 149 counts the input second pulsesignal D62 during the enable-signal supply time. And in response to thethird enable signal S40 to the third counter circuit 150, this circuit150 counts the input third pulse signal D63 during the enable-signalsupply time.

Supposing here that each counter circuit is so controlled as to be resetwhen an enable signal has been supplied thereto 10 times for example,the first counter circuit 148 is reset after outputting a first countvalue D64 upon completion of supply of the first enable signal S38thereto. The same operation is performed with respect to the othercounter circuits 149 and 150 as well.

A converter circuit 151 estimates the relative velocity between therelevant mobile station and the base station from each of the first tothird count values D64-D66 and then outputs first to third travelvelocity data D67, D68 and D69 which correspond respectively to thecount values D64-D66. The travel velocity data D67, D68 and D69 areinputted successively to the synthesizer circuit 125 shown in FIG. 34.

The synthesizer circuit 125 once stores the travel velocity data D67,D68 and D69 in mutually different memory areas and, upon completestorage of the three data D67, D68 and D69, the circuit 125 selects themaximum value and then outputs the same as a travel velocity D70 finallyobtained.

Also in the 24th embodiment described above, a high precision isattainable in detecting the travel velocity of the mobile station, as inthe aforementioned 22nd embodiment.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to detect the travelvelocity, travel distance and acceleration of a mobile station fromradio communication waves. And a received level can be detectedadaptively to the travel velocity of the mobile station.

Consequently it becomes possible to perform, on the basis of the travelvelocity, travel distance and acceleration thus detected, a variety ofoperations inclusive of hand-off control, transmission power control,radio network control such as radio channel allocation control, andservice control as well.

We claim:
 1. A travel velocity detecting apparatus in a mobilecommunication system comprising:control means for outputting a pluralityof control signals to perform time-division multiplex communication;receiving means connected operatively to said control means forreceiving, through time-division multiplex communication based on saidcontrol signals, radio waves of different frequencies transmitted from aplurality of base stations; velocity detector means including:leveldetector means connected operatively to both of said control means andsaid receiving means for detecting a level of a signal outputted fromsaid receiving means; sampling means connected operatively to said leveldetector means for sampling said signal level; memory means connectedoperatively to said sampling means for storing a sampled level,outputting the same therefrom in an order of storage; differencecalculator means connected operatively to both of said memory means andsaid sampling means for calculating a difference between the receivedlevels outputted respectively from said sampling means and said memorymeans; comparator means connected operatively to said differencecalculator means for comparing the difference, which is obtained in saiddifference calculator means, with a preset threshold value to therebydetermine whether said difference is in excess of said threshold value;a plurality of counter means connected operatively to said comparatormeans for counting, only during a supply of said plurality of controlsignals, comparison results outputted from said comparator means,thereby counting a number of times that said difference has exceededsaid threshold value; and converter means connected operatively to saidplurality of counter means for estimating relative travel velocitiesbetween a relevant mobile station and said plurality of base stations onthe basis of count values obtained in said counter means; and meansconnected operatively to said velocity detector means for selecting amaximum value out of the relative travel velocities obtained in saidvelocity detector means, and delivering the selected maximum value as anoutput.
 2. A travel velocity detecting apparatus in a mobilecommunication system comprising:a plurality of diversity receiving meansfor detecting received radio waves to thereby obtain received data anddetecting powers of said radio waves; comparator means connectedoperatively to said plurality of receiving means for mutually comparingthe powers detected by said receiving means so as to determine which ofsaid powers is greater: selector means connected operatively to saidreceiving means and said comparator means for selecting one of saidreceived data in accordance with a comparison result outputted from saidcomparator means; variation detector means connected operatively to saidcomparator means for detecting variations of said comparison result;counter means connected operatively to said variation detector means forcounting, only for a preset time, a number of the variations detected bysaid variation detector means; and converter means connected operativelyto said counter means for calculating a relative travel velocity betweena relevant mobile station and an opposite transmitting station on thebasis of a count value obtained by said counting operation.
 3. A travelvelocity detecting apparatus in a mobile communication systemcomprising:switching means for alternately switching a plurality ofantennas of different branches and alternately outputting first andsecond radio waves received by said antennas of two branches; fieldintensity detector means connected operatively to said switching meansfor detecting electric field intensities of said first and second radiowaves; memory means connected operatively to said field intensitydetector means for storing the field intensity of said first radio wavesand outputting said field intensity therefrom in the order of storage;comparator means connected operatively to said field intensity detectormeans and said memory means, for comparing the field intensity of thesecond radio waves with the field intensity of the first radio wavesoutputted from said memory means, thereby determining which of saidfield intensities is greater; variation detector means connectedoperatively to said comparator means for detecting variations of acomparison result outputted from said comparator means; counter meansconnected operatively to said variation detector means for counting,only for a preset time, a number of the variations detected by saidvariation detector means; and converter means connected operatively tosaid counter means for calculating a relative travel velocity between arelevant mobile station and an opposite transmitting station on thebasis of a count value obtained by said counting operation.
 4. A travelvelocity detecting apparatus in a mobile communication systemcomprising:a plurality of receiving means for receiving radio waves anddetecting powers of said radio waves; comparator means connectedoperatively to said plurality of receiving means for mutually comparingthe powers detected by said receiving means so as to determine which ofsaid powers is greater; variation detector means connected Operativelyto said comparator means for detecting variations of a comparison resultoutputted from said comparator means; counter means connectedoperatively to said variation detector means for counting, only for apreset time, a number of the variations detected by said variationdetector means; converter means connected operatively to said countermeans for calculating a relative travel velocity between a relevantmobile station and an opposite transmitting station on the basis of acount value obtained by said counting operation; and corrector meansoperatively connected in a posterior stage to one of said receivingmeans for correcting any gain difference existing between said pluralityof receiving means.
 5. A travel velocity detecting apparatus in a mobilecommunication system comprising:a plurality of receiving means forreceiving radio waves and detecting powers of said radio waves;comparator means connected operatively to said plurality of receivingmeans for mutually comparing the powers detected by said receiving meansso as to determine which of said powers is greater; variation detectormeans connected operatively to said comparator means for detectingvariations of a comparison result outputted from said comparator means;counter means connected operatively to said variation detector means forcounting, only for a preset time, a number of the variations detected bysaid variation detector means; and converter means connected operativelyto said counter means for calculating a relative travel velocity betweena relevant mobile station and an opposite transmitting station on thebasis of a count value obtained by said counting operation; wherein saidconverter means includes:a table composed of integral number data of "0,1, 2, . . . , N" and travel velocity data assigned correspondingly tosaid integral number data, and means for retrieving, in response toinput of said count value to said converter means, the travel velocitydata assigned correspondingly to the integral number data correspondingto said count value, and then outputting a retrieved travel velocitydata as said relative travel velocity.
 6. A travel velocity detectingapparatus in a mobile communication system comprising:a plurality ofreceiving means for receiving radio waves and detecting powers of saidradio waves; comparator means connected operatively to said plurality ofreceiving means for mutually comparing the powers detected by saidreceiving means so as to determine which of said powers is greater;variation detector means connected operatively to said comparator meansfor detecting variations of a comparison result outputted from saidcomparator means; counter means connected operatively to said variationdetector means for counting, only for a preset time, a number of thevariations detected by said variation detector means; and convertermeans connected operatively to said counter means for calculating arelative travel velocity between a relevant mobile station and anopposite transmitting station on the basis of a count value obtained bysaid counting operation; wherein said converter means includes means toperform such operations that a conversion equation v=(N_(BC) /C)×λ forcalculating the travel velocity v is programmed, in which N_(BC) denotessaid number of variations, λ denotes a wavelength of said radio waves,and C is a constant, said travel velocity v is calculated bysubstituting said count value for N_(BC) in the programmed conversionequation, and the travel velocity v thus obtained is outputted as saidrelative travel velocity.
 7. A travel velocity detecting apparatus in amobile communication system comprising:a plurality of receiving meansfor receiving radio waves and detecting powers of said radio waves;comparator means connected operatively to said plurality of receivingmeans for mutually comparing the powers detected by said receiving meansso as to determine which of said powers is greater; variation detectormeans connected operatively to said comparator means for detectingvariations of a comparison result outputted from said comparator means;counter means connected operatively to said variation detector means forcounting, only for a preset time, a number of the variations detected bysaid variation detector means; and converter means connected operativelyto said counter means for calculating a relative travel velocity betweena relevant mobile station and an opposite transmitting station on thebasis of a count value obtained by said counting operation; wherein saidconverter means includes:a plurality of tables equal in number to kindsof wavelengths of received radio waves, and means for detecting thewavelengths, each of said tables being composed of integral number dataof "0, 1, 2, . . . , N" and travel velocity data assignedcorrespondingly to said integral number data; wherein the tablecorresponding to the wavelength detected by said means is retrieved, andthe travel velocity data assigned correspondingly to the integral numberdata corresponding to said count value is retrieved from said table tothereby detect said relative travel velocity.
 8. A travel velocitydetecting apparatus in a mobile communication system comprising:aplurality of receiving means for receiving radio waves and detectingpowers of said radio waves; comparator means connected operatively tosaid plurality of receiving means for mutually comparing the powersdetected by said receiving means so as to determine which of said powersis greater; variation detector means connected operatively to saidcomparator means for detecting variations of a comparison resultoutputted from said comparator means; counter means connectedoperatively to said variation detector means for counting, only for apreset time, a number of the variations detected by said variationdetector means; converter means connected operatively to said countermeans for calculating a relative travel velocity between a relevantmobile station and an opposite transmitting station on the basis of acount value obtained by said counting operation; and wavelength detectormeans for detecting wavelengths of the radio waves; wherein saidconverter means includes means to perform such operations that aconversion equation v=(N_(BC) /C)×λ for calculating the travel velocityv is programmed, in which N_(BC) denotes said number of variations, λdenotes the wavelength of said radio waves, and C is a constant, thensaid travel velocity v is calculated by substituting the wavelength,which is detected in said wavelength detector means, for λ in theprogrammed conversion equation, and further by substituting said countvalue for N_(BC) in said equation, and the travel velocity v thusobtained is outputted as said relative travel velocity.
 9. A travelvelocity detecting apparatus in a mobile communication systemcomprising:a plurality of receiving means for receiving radio waves anddetecting powers of said radio waves; comparator means connectedoperatively to said plurality of receiving means for mutually comparingthe powers detected by said receiving means so as to determine which ofsaid powers is greater; variation detector means connected operativelyto said comparator means for detecting variations of a comparison resultoutputted from said comparator means; counter means connectedoperatively to said variation detector means for counting, only for apreset time, a number of the variations detected by said variationdetector means; and converter means connected operatively to saidcounter means for calculating a relative travel velocity between arelevant mobile station and an opposite transmitting station on thebasis of a count value obtained by said counting operation; maximumvalue detector means for detecting a maximum value of said relativetravel velocity and outputting the detected maximum value as a relativetravel velocity.
 10. A travel velocity detecting apparatus in a mobilecommunication system comprising:level detector means for detecting areceived level of radio waves; sampling means connected operatively tosaid level detector means for sampling said received level; memory meansconnected operatively to said sampling means for storing a sampled leveland outputting the same therefrom in an order of storage; differencecalculator means connected operatively to said memory means and saidsampling means, for calculating a difference between the received levelsoutputted from said sampling means and said memory means; comparatormeans connected operatively to said difference calculator means forcomparing the difference, which is obtained from said differencecalculator means, with a predetermined threshold value to make adecision as to whether the difference is in excess of the thresholdvalue; counter means connected operatively to said comparator means forcounting, for a preset time, a comparison results outputted from saidcomparator means, thereby obtaining a number of times that saiddifference has exceeded said threshold value; and converter meansconnected operatively to said counter means for estimating a relativetravel velocity between a relevant mobile station and an oppositetransmitting station on the basis of a count value obtained in saidcounter means.
 11. The travel velocity detecting apparatus in a mobilecommunication system according to claim 10, further comprising maximumvalue detector means for detecting a maximum value of said relativetravel velocity and outputting the detected maximum value as a relativetravel velocity.
 12. A received power level measuring apparatus in amobile station comprising:a plurality of receiving means for detectingreceived levels of radio waves; comparator means connected operativelyto said plurality of receiving means for mutually comparing the receivedlevels detected in said receiving means, thereby determining which ofsaid received levels is higher; variation detector means connectedoperatively to said comparator means for detecting a variation of acomparison result outputted from said comparator means; counter meansconnected operatively to said variation detector means for counting, upto a preset value, a number of the variations detected by said variationdetector means; and averaging means connected operatively to saidcounter means and one of said receiving means, for temporally averagingone of said received levels until a count value obtained in said countermeans reaches a preset value, and outputting an average value thusobtained as a received level.
 13. A received power level measuringapparatus in a mobile station comprising:a plurality of diversityreceiving means for demodulating received radio waves to obtain receiveddata and detecting the received levels of said radio waves; comparatormeans connected operatively to said plurality of receiving means formutually comparing the received levels detected in said receiving means,thereby determining which of said received levels is higher; selectormeans connected operatively to said plurality of receiving means andsaid comparator means, for selecting one of said received data inaccordance with a comparison result outputted from said comparatormeans; variation detector means connected operatively to said comparatormeans for detecting a variation of said comparison result; counter meansconnected operatively to said variation detector means for counting, upto a preset value, a number of the variations detected by said variationdetector means; and averaging means connected operatively to saidcounter means, for temporally averaging one of said received levelsuntil a count value obtained in said counter means reaches a presetvalue, and outputting an average value thus obtained as a receivedlevel.
 14. A received power level measuring apparatus in a mobilestation comprising:switching means for alternately switching a pluralityof antennas of different branches and alternately outputting first andsecond radio waves received by said antennas; field intensity detectormeans connected operatively to said switching means for detectingelectric field intensities of said first and second radio waves; memorymeans connected operatively to said field intensity detector means forstoring the field intensity of said first radio waves and outputtingsaid field intensity therefrom in an order of storage; comparator meansconnected operatively to said field intensity detector means and saidmemory means, for comparing the field intensity of the second radiowaves with the field intensity of the first radio waves outputted fromsaid memory means, thereby determining which of said field intensitiesis greater; variation detector means connected operatively to saidcomparator means for detecting the variations of a comparison resultoutputted from said comparator means; counter means connectedoperatively to said variation detector means for counting, only for apreset time, a number of the variations detected by said variationdetector means; and averaging means for temporally averaging one of saidfield intensities until a count value obtained in said counter meansreaches a preset value, and outputting an average value thus obtained asa received level.
 15. The received power level measuring apparatus in amobile station according to claim 12, further comprising;corrector meansconnected operatively to a stage, posterior to one of said plurality ofreceiving means, for correcting any gain difference existing betweensaid receiving means.
 16. The received power level measuring apparatusin a mobile station according to claim 12, further comprising;selectormeans connected operatively to stages posterior to said plurality ofreceiving means for, in accordance with the comparison result outputtedfrom said comparator means, selecting a higher one of the receivedlevels obtained in said receiving means, wherein a received levelselected by said selector means is inputted to said averaging means. 17.The received power level measuring apparatus in a mobile stationaccording to claim 12, wherein said variation detector means and saidaveraging means are connected to each other in such a manner that thenumber of the variations is inputted to said averaging means, and whensaid number remains unchanged for a predetermined time, the samplevalues of said received levels are partially excluded from the averagingcalculation executed by said variation detector means.
 18. The receivedpower level measuring apparatus in a mobile station according to claim12, further comprising:frequency counter means for counting a frequencyof sampling said received levels; calculator means connected operativelyto said frequency counter means for changing a frequency count value,which is obtained in said frequency counter means, to a fixed value sothat the count value obtained in said counter means may become slightlysmaller than a half of said frequency count value; count valuecomparator means connected operatively to said counter means and saidcalculator means, for delivering an output which represents a differencebetween the count value and the frequency count value; and oscillatormeans connected operatively to said count value comparator means forcontrolling said sampling frequency in accordance with the differenceobtained in said count value comparator means.
 19. The travel velocitydetecting apparatus in a mobile communication system according to claim10, further comprising:receiving means connected operatively to a stageanterior to said level detector means for receiving wide-band radiowaves and demodulating the received radio waves; and a narrowband filterconnected operatively to said receiving means for limiting the frequencybandwidth of a signal demodulated by said receiving means; wherein saidlevel detector means detects a level of a signal outputted from saidnarrow-band filter.
 20. A travel velocity detecting apparatus in amobile communication system comprising:receiving means for receiving anddemodulating wide-band radio waves; a plurality of narrow-band filtersconnected operatively to said receiving means for limiting a frequencybandwidth of a signal demodulated by said receiving means, said filtersbeing such that the center frequencies thereof are so spaced apart fromeach other as to cause no correlation between level variations obtained;a plurality of level detector means connected operatively to saidplurality of narrow-band filters respectively for detecting levels ofsignals outputted from said narrowband filters respectively; comparatormeans connected operatively to said plurality of level detectors formutually comparing the levels detected in said level detector means,thereby determining which of said levels is higher; variation detectormeans connected operatively to said comparator means for detecting avariation of a comparison result outputted from said comparator means;counter means connected operatively to said variation detector means forcounting, only for a preset time, a number of variations detected bysaid variation detector means; and converter means connected operativelyto said counter means for estimating a relative travel velocity betweena relevant mobile station and an opposite transmitting station on thebasis of a count value obtained by said counting operation.
 21. A travelvelocity detecting apparatus in a mobile communication systemcomprising:receiving means for receiving and demodulating wide-bandradio waves; a plurality of narrow-band filters connected operatively tosaid receiving means for limiting a frequency bandwidth of a signaldemodulated by said receiving means; level detector means connectedoperatively to said narrow-band filters for detecting a level of asignal outputted from each of said narrow-band filters; a plurality ofvelocity detecting units connected in parallel to said receiving means,each unit including:velocity detector means which has sampling meansconnected operatively to said level detector means for sampling a leveldetected by said level detector means, memory means connectedoperatively to said sampling means for storing a sampled level andoutputting the same therefrom in an order of storage, differencecalculator means connected operatively to both of said memory means andsaid sampling means for calculating a difference between the receivedlevels outputted from said sampling means and said memory means,comparator means connected operatively to said difference calculatormeans for comparing the difference, which is obtained in said differencecalculator means, with a preset threshold value to thereby determinewhether said difference is in excess of said threshold value, countermeans connected operatively to said comparator means for counting, for apreset time, comparison results outputted from said comparator means,thereby counting a number of times that said difference has exceededsaid threshold value, and converter means connected operatively to saidcounter means for estimating a relative travel velocity between arelevant mobile station and an opposite transmitting station on thebasis of a count value obtained in said counter means; wherein thecenter frequencies of said narrow-band filters are so spaced apart fromeach other as to cause no correlation between the level variations ofthe passed signals; and maximum value detector means connectedoperatively to said plurality of velocity detecting units for detectinga maximum value out of relative travel velocities outputted from saidvelocity detecting units.
 22. The travel velocity detecting apparatus ina mobile communication system according to claim 19, wherein saidapparatus is applied to a mobile station in a CDMA (code divisionmultiple access) system.
 23. A travel velocity detecting apparatus in amobile communication system comprising:branch means for simultaneouslyreceiving radio waves of different frequencies transmitted from aplurality of base stations and branching a received radio wave signalgroup into a plurality of signals; a plurality of receiving meansconnected operatively to signal output terminals of said branch meansfor demodulating signals of the different frequencies respectively froma plurality of signal groups outputted from said branch means; aplurality of velocity detector means connected operatively to saidplurality of receiving means respectively, each of said velocitydetector means having:level detector means for detecting a level of asignal outputted from said receiving means; sampling means connectedoperatively to said level detector means for sampling the level detectedby said level detector means; memory means connected operatively to saidsampling means for storing a sampled level and outputting the sametherefrom in an order of storage; difference calculator means connectedoperatively to both of said memory means and said sampling means forcalculating a difference between received levels outputted from saidsampling means and said memory means; comparator means connectedoperatively to said difference calculator means for comparing thedifference, which is obtained in said difference calculator means, witha preset threshold value to thereby determine whether the difference isin excess of the threshold value; counter means connected operatively tosaid comparator means for counting, for a preset time, comparisonresults outputted from said comparator means, thereby counting a numberof times that said difference has exceeded said threshold value; andconverter means connected operatively to said counter means forestimating a relative travel velocity between a relevant mobile stationand an opposite transmitting station on the basis of a count valueobtained in said counter means; and synthesizer means connectedoperatively to said plurality of velocity detector means for selecting amaximum value out of the relative travel velocities obtained in saidvelocity detector means, and delivering a selected maximum value as anoutput.
 24. The travel velocity detecting apparatus in a mobilecommunication system according to claim 23, wherein:said velocitydetector means is installed in each of said base stations, and saidsynthesizer means is installed in a network control station which servesto control said base stations; and when radio waves transmitted from onemobile station are received by said plurality of base stations, arelative travel velocity between a relevant station and said mobilestation is detected from the received radio waves by each of thevelocity detector means installed in said base stations and then istransmitted to the synthesizer means in said network control station,and subsequently said synthesizer circuit selects a maximum value out ofthe plural relative travel velocities received and delivers a selectedmaximum value as an output.